Ankle sprains in the general population typically occur as a result of either excessive inversion or excessive eversion. An inversion ankle sprain is the internal rotation of the ankle joint; i.e., rolling the foot inward or medially, and overstretching and usually injuring the outer ligaments in the ankle. This accounts for about 90 percent of all ankle sprains. An eversion ankle sprain is the external rotation of the ankle joint; i.e., rolling the foot outward or laterally.
The ankle is an assembly of bones held together by a number of soft tissues such as muscles, ligaments, tendons, and cartilage. In the typical ankle injury, a traumatic impact or force causes the foot to invert or evert relative to the lower leg. When the off-centered force induces inversion or eversion of the foot relative to the lower leg in excess of the natural limits of the soft tissue structures, that soft tissue is damaged. The injury may include stretching or tearing of the soft tissues and, if severe enough, damage or fracture to the bones in the ankle joint, lower leg, and foot.
Ankle braces and supports are prescribed as a treatment for an ankle sprain or fracture, or to prevent further injury to the weakened joint. It should support and stabilize the ankle and foot to limit inversion and eversion, but should not overly limit the flexion motions associated with the foot motions of the wearer walking, running, lunging, pivoting, etc. If the injured ankle is substantially immobilized by the ankle brace, rehabilitation is delayed and a stiff ankle may result, which opens the possibility for re-injury.
Injuries to ankles typically require the application of ankle braces, which must be repeatedly applied and removed at short intervals during the rehabilitation period. Thus, ease and rapidity of application and removal are important to the wearer. The ankle brace cannot be complicated so that it is easy for the wearer to physically put on and take off, and should also be comfortable to wear.